Some individuals with type 1 diabetes (T1D) use the DIY Kit RileyLink Loop System (Loop) during exercise to avoid hypoglycemia and maintain optimal glucose levels; however, the system has no regulatory approval. This exploratory retrospective analysis assessed carbohydrate (CHO) requirements for maintaining glucose in target range (70-180 mg/dL) during and after 2 days of prolonged cycling, comparing the Loop with rtCGM plus insulin pump (rtCGM+P). Seven T1D adults (2 female/5 male, age 41±11 years, 6.1±0.8% A1C) were enrolled. Cycling was divided into two parts each day (Part 1, 28 miles; Part 2, 17 miles) with an hour lunch between parts. CHO intake was lower in the Loop group vs. rtCGM+P on Day1. (Table 1) More CHOs were required on Day2 than Day1 with Loop use (rtCGM+P users did not cycle on Day2). Prandial insulin doses were notably lower at the Day2 lunch meal vs. Day1 44 g CHO/IU vs. 6 g CHO/IU. Loop users vs. rtCGM+P users spent notably less time <70 mg/dL on Day 1 (5.4 ± 4.4% vs. 12 ± 17%, respectively) and Post Exercise Day (3.8 ± 2.8% vs. 0.5 ± 0.7%, respectively). Time spent within 70 - 180 mg/dL were comparable on Day1 (84 ± 16% vs. 82 ± 17%, respectively) and Post Exercise Day (88 ± 10% vs. 91 ± 11%, respectively. Use of the Loop was associated with lower CHO requirements during prolonged exercise. Loop settings must be adjusted before and after exercise to maintain glucose levels <220 mg/dL.

M. Mueller-Korbsch: Research Support; Self; Dexcom, Inc., Menarini Group, Novo Nordisk A/S. L. Fruehwald: None. M. Heer: None. M. Fangmeyer-Binder: None. D. Reinhart-Mikocki: None. P. Fasching: None.

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